The present invention relates to spray cooling a round ingot made by continuous casting.
Continous casting requires extensive cooling of the ingot as it is withdrawn and descends from the mold. It is a known practice to arrange spray nozzles annularly around the ingot and to discharge water through these nozzles, towards the ingot's surface. Other modes of distributing the nozzles are known, which is needed, for example, in case of slab ingots.
It was found that round ingots cannot be uniformly cooled in this fashion. The jet exiting from a nozzle ingot be approximated by a cone. That cone intersects the curved surface of the ingot. The rate of water inpacting on that surface per unit area differs around the ingot accordingly, so that cooling is non-uniform indeed. Inevitable, non-uniform cooling produces non-uniform skin thickness of the solidifying ingot, being still liquidous in its interior for quite a distance from the mold. Such non-uniformity inevitably increases the danger of skin rupture. This being the operation conditions, it is apparent that low withdrawal rates for ingots are required to ensure a wide margin of safety. The problem is compounded if, for any reason, a nozzle no longer functions as that introduces into the process a strong additional component as to non-uniformity. The nozzle has to be replaced or repaired immediately, but either procedure requires halting of the machine and of the casting process.